Detective Inspector Mark Colman, of Kirklees District CID, said: “We would like to hear from anyone who witnessed anything suspicious around the time of these incidents for who has had similar approaches.

“We urge people to remain vigilant and to contact the police immediately if they see anyone acting suspiciously in their street or calling at homes. We also want people to keep an eye out for their elderly neighbours.

“If you see someone calling on them and you’re suspicious then contact the police straight away.

“Do not allow strangers into your home if they are not from a company or organisation that is expected for a pre-arranged visit.

“Keep the door on a chain and ask to see their identification badge and contact the company they claim to work for. Genuine callers will not mind waiting or coming back.

“If you are in any doubt, contact the police.”

The alleged conman from February 10 is a white man aged in his late forties, medium build, with dark stubble and a mole on his nose.

The suspect from the crime on January 21 is also a white man who is about 5ft 5ins tall, stocky, with short mousy hair that was combed back. He was wearing a dark-coloured jacket and was in a white van with writing on the side.